Number of asymmetric trees with a forbidden limb of length 3.

Terms

a(0) =1a(1) =1a(2) =0a(3) =0a(4) =0a(5) =0a(6) =0a(7) =0a(8) =0a(9) =0a(10) =0a(11) =1a(12) =2a(13) =6a(14) =11a(15) =25a(16) =49a(17) =105a(18) =211a(19) =444a(20) =903a(21) =1880a(22) =3865a(23) =8042a(24) =16658a(25) =34764a(26) =72484a(27) =151856a(28) =318418a(29) =669934